In this project, we are investigating host and Neisseria gonorrhoeae factors which affect the human immune responses and pathogenesis of infection. Humoral immune responses have been analyzed and late acting complement component deficiencies have been detected. Current emphasis is on study of factors such as seminal plasma which alter the humoral immune responses and may be important in the genital tract immune mechanisms. A second emphasis of this project is the study of factors which promote the attachment and invasion of Neisseria gonorrhoeae to eukaryotic cells and genital tissues of human origin. Currently, studies are emphasizing the kinetic analysis of attachment and the factors which affect this attachment by utilizing Langmuir isotherm adsorption techniques.